Motorway surveying? - OldPeculiar
This morning on the M4 between Chippenham and Swindon I passed a "survey van" with a big sign on the back saying "Lane surveying in progress" It certainly seemed to be doing something as there was a large flashing strip light attached to the back with a piece of rubber hanging of the back of the van to hide it from drivers eyes.

I'm guessing that this is a precursor to another lane closure on that stretch for re-surfacing. Has anyone else seen these vans in their area, have they invariably been followed by roadwork's?
Motorway surveying? - Dwight Van Driver
They are at it all the time for the very reason you state. Highways Agency can then assess the state of wear, work out re-surfacing schedule and costings and when the time comes make the closure Order, engage Contractors etc etc.

DVD